Working principle: The valve seat is refaced in a lathe-type facing action. While the single point cutting tool is rotated in a circle around the valve seat, a feed gear ensures a continuous outward transverse feed motion under the proper seat angle.
This angle is defined by an inclined slideway in the exchangeable adapter head. A pilot inserted in the valve guide aligns the VDS1A in centerline with the valve guide. A swiveling guide arm is provided below the crank handle for additional support. To eliminate run out when the VDS 1A is rotated around the pilot, the swiveling guide arm is locked in place either by a steady rest which is mounted on the cylinder head or by means of the Hunger K2000 cylinder head stand. Handling: Operation is straightforward. First, insert the pilot into the valve guide. Then place the VDS1A over the pilot and lock swiveling guide arm in place. Lower the VDS1A until the cutting tool is just in contact with the valve seat. Turn rapid tool traverse to position the cutting tool in front of the inner edge of the valve seat. Turn micrometer downfeed to set the desired depth of cut. Rotate VDS1A with crank handle to reface the valve seat in centerline with the valve guide under the correct seat angle. If required, the refaced valve seat can be narrowed by using the side cutting edges of the cutting tool to machine the upper and lower edges of the valve seat. Benefits: No setting gauges, no time consuming measurements or guesswork Lathe-type refacing removes material from the hardened and burned spots of the seat gradually from the side and, therefor, no upward spring action resulting in chatter marks will occur. The refaced valve seat has a flawless concentric texture for a complete valve seal. Because the depth of cut is preset by a micrometer downfeed mechanism, even an unexperienced operator is able to maintain positive control over the material being removed from the valve seat. Roundness, concentricity and surface finish of the refaced seat are within manufacturers´ specifications or even better. The carbide-tipped cutting tools can be resharpened on standard tool sharpeners